Patent specification DE-C-34 33 412 discloses a means for calculating the optimum settings for the adjustable lens and image carriers of a photographic camera. The camera is so designed that three points of an object can be focused on the photographic image. According to the Scheimpflug condition, the aim is to achieve sharp imaging of the points of the object For this purposes, the three different points of the object are brought into sharp focus one after another and the corresponding values are delivered via a keyboard to a computer which then calculates and displays the correct setting of the camera in accordance with the Scheimpflug condition. In other embodiments of the camera, sensor elements are provided which calculate the sharpness of the selected image point. In addition, motors are provided which automatically bring the lens and image carrier to the desired position.
The international patent application WO 91/10157 describes a device and a process for focusing a photographic camera. The lens and image plane are pivotably arranged in relation to one another so that the camera can be set to positions which meet the Scheimpflug condition. To this end, the user selects two points of the object which are to be sharply imaged. The distance of these points to the horizontal axis of symmetry of the image plane is measured and the data fed to a computer which then calculates the values of the settings for the lens and the image plane.
In order to give a small camera the imaging properties of a studio camera, a number of lenses are available where the lens system can be moved parallel to the image plane (see the article "Tilt and Shift"; FOTO magazine, February, 1996, pages 44 to 49). The lenses are extremely expensive and automatic setting to obtain optimum focusing of an object area is not possible.